Solid-state image pickup device

ABSTRACT

A solid-state image pickup device in which no warp occurs in a solid-state image pickup element chip is provided. A solid-state image pickup device, including a solid-state image pickup element chip on which a plurality of solid-state image pickup elements are mounted, a wiring substrate electrically connected to the solid-state image pickup element chip and adapted to transmit signals from each one of a plurality of solid-state image pickup elements, and a protection cap provided on a light incident side of the solid-state image pickup element chip and adapted to protect the solid-state image pickup element chip, is characterized in that the solid-state image pickup element chip is formed on a substrate with a thermal expansion coefficient equal to that of the protection cap, and the substrate and the protection cap are sealed with a sealing resin.

BACKGROUND OF THE INVENTION Field of the Invention

[0001] The present invention relates to a solid-state image pickupdevice such as a CCD or CMOS image sensor used in a digital camera orthe like.

[0002] Conventionally, a solid-state image pickup device such as a CCDor CMOS image sensor is utilized in a digital camera or the like and itsapplication field expands. As the product becomes more downsized andlower-profile, a solid-state image pickup device which is more downsizedand lower-profile is strongly demanded. In order to meet this demand, asolid-state image pickup device using a TAB (Tape-Automated Bonding)tape as described in, e.g., U.S. Pat. No. 5,506,401, is available.

[0003]FIG. 7 is a sectional view of a solid-state image pickup devicedescribed in the above reference. As shown in FIG. 7, in a conventionalsolid-state image pickup device, a TAB tape 2 with an insulating film 22and copper leads 21 is adhered to one surface of a protection cap 3 withan adhesive 10.

[0004] The TAB tape 2 is connected onto bumps 6 formed on electrode pads5 of a solid-state image element pickup chip 1, on which a plurality ofsolid-state image pickup elements 7 are mounted, through an anisotropicconductive film 9. Alternatively, the TAB tape 2 may be connected to thebumps 6 directly by ultrasonic bonding.

[0005] The solid-state image pickup element chip 1 and protection cap 3are sealed at their peripheries with a sealing resin 8. The solid-stateimage pickup device using such a TAB tape 2 can be formed more downsizedand lower-profile than, e.g., a wire-bonded ceramic package.

[0006] According to the conventional technique, however, since thethermal expansion coefficient of the solid-state image pickup elementchip differ from that of the protection cap, the heating in themanufacturing process or changes in temperature during use warps thesolid-state image pickup element chip. Among countermeasures to preventthis, a protection cap with a thermal expansion coefficientcomparatively close to that of silicon as the main material of thesolid-state image pickup element chip may be used.

[0007] However, because of the cost and other characteristic aspects, aprotection cap with a thermal expansion coefficient largely differentfrom that of silicon must often be used. Therefore, another solution hasbeen sought for.

[0008] When the protection cap and solid-state image pickup element chipare sealed at their peripheries by heating, air between the protectioncap and solid-state image pickup element chip expands by heating andescapes from the sealed structure. If encapsulation is completed in thisstate, air in the sealed structure that has been restored to roomtemperature shrinks, and a warp occurs in the solid-state image pickupelement chip. As a countermeasure for this, a portion free from thesealing resin is reserved in advance so a vent hole is formed thereafter adhesion, and this portion is closed later on and encapsulation iscompleted. In this case, however, the process increases, leading to anincrease in cost.

[0009] Shrinkage of the sealing resin itself during hardening also warpsthe solid-state image pickup element chip. When a warp occurs in thesolid-state image pickup element chip in the above manner, the focalpoint differs among the pixels of the solid-state image pickup elements,and the image quality degrades.

SUMMARY OF THE INVENTION

[0010] It is, therefore, an object of the present invention to provide asolid-state image pickup device in which a warp does not occur in thesolid-state image pickup element chip.

[0011] In order to achieve the above object, according to the presentinvention, there is provided a solid-state image pickup devicecomprising a solid-state image pickup element chip on which a pluralityof solid-state image pickup elements are mounted, and a protection capprovided on a light incident side of the solid-state image pickupelement chip and adapted to protect the solid-state image pickup elementchip, characterized in that the solid-state image pickup element chip isformed on a substrate with a thermal expansion coefficient equal to thatof the protection cap, and the substrate and the protection cap aresealed with a sealing resin.

[0012] According to the present invention, there is also provided asolid-state image pickup device comprising a solid-state image pickupelement chip on which a plurality of solid-state image pickup elementsare mounted, and a protection cap provided on a light incident side ofthe solid-state image pickup element chip and adapted to protect thesolid-state image pickup element chip, characterized in that thesolid-state image pickup element chip is formed on a substrate made ofthe same material as that of the protection cap through alight-shielding layer that shields light, and the substrate and theprotection cap are sealed with a sealing resin.

[0013] More specifically, according to the present invention, theprotection cap and solid-state image pickup element chip with differentthermal expansion coefficients are not directly adhered to each other,so no warp is caused in the solid-state image pickup element chip by anambient temperature change.

[0014] According to the present invention, the solid-state image pickupelement chip is sealed between the protection cap and substrate, and isnot fixed to the protection cap. Thus, even when the atmosphericpressure in the sealed structure changes or the sealing resin shrinksduring hardening, no warp occurs in the solid-state image pickupelements.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a sectional view of a solid-state image pickup deviceaccording to the first embodiment of the present invention;

[0016]FIG. 2 is a plan view of FIG. 1;

[0017]FIG. 3 is an exploded perspective view of FIG. 1;

[0018]FIG. 4 is a sectional view of a solid-state image pickup deviceaccording to the second embodiment of the present invention;

[0019]FIG. 5 is a sectional view of a solid-state image pickup deviceaccording to the third embodiment of the present invention;

[0020]FIG. 6 is a sectional view of a solid-state image pickup deviceaccording to the fourth embodiment of the present invention; and

[0021]FIG. 7 is a sectional view of a conventional solid-state imagepickup device.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

[0023] (First Embodiment)

[0024]FIG. 1 is a sectional view of a solid-state image pickup deviceaccording to the first embodiment of the present invention. FIG. 2 is aplan view of FIG. 1. FIG. 3 is an exploded perspective view of FIG. 1.FIG. 1 shows a state wherein a TAB tape 2 is connected to bumps 6 formedon electrode pads 5 of a solid-state image pickup element chip 1. TheTAB tape 2 can be connected, e.g., by ultrasonic bonding or through ananisotropic conductive film or conductive paste.

[0025] To form the bumps 6, gold is usually used. Alternatively, thebumps 6 may be formed of another metal such as copper or nickel, or analloy, and be plated with gold. In the TAB tape 2, a plurality of copperleads 21 are formed on an insulating film 22. The insulating film 22 isformed of a resin film such as a polyimide film.

[0026] A protection cap 3 is arranged on a light incident side of thesolid-state image pickup element chip 1, and a substrate 4 is arrangedon the lower surface of the solid-state image pickup element chip 1,such that they sandwich the solid-state image pickup element chip 1. Theprotection cap 3 is made of, e.g., non-alkali glass or quartz, andtransmits light through it. Alternatively, a protection cap made of aresin having light transmission properties, e.g., an acrylic resin, maybe used. An optical low-pass filter or infrared cutting filter may beformed on the protection cap 3.

[0027] Usually, a light-shielding film is formed on the periphery of theprotection cap 3 so as to cover the bumps 6 and copper leads 21, so theywill not cause diffused reflection of the incident light that adverselyaffects the image.

[0028] The substrate 4 has a thermal expansion coefficient equal to thatof the protection cap 3, and is formed of, e.g., a glass substrate,ceramic substrate, metal substrate, or resin substrate, or by stackingthem.

[0029] The protection cap 3 and substrate 4 are sealed at theirperipheries with a sealing resin 8 to hermetically seal the solid-stateimage pickup element chip 1. For example, the sealing resin 8 is anepoxy-, acrylic, or phenol-based resin, and can be of either thermoset,ultraviolet-curing, or ultraviolet-curing/thermoset type. A filler maybe mixed in the sealing resin 8 to improve the reliability. The fillermay be either an inorganic or organic material, and is made of, e.g.,silica.

[0030] According to this embodiment, since the protection cap 3 isadhered to the substrate 4 with a thermal expansion coefficient equal tothat of the protection cap 3, a force that warps the solid-state imagepickup element chip 1 is not substantially generated by an ambienttemperature change. Since the solid-state image pickup element chip 1 isnot directly influenced by a change in atmospheric pressure in thesealed structure or by shrinkage of the sealing resin 8 duringhardening, a warp in the solid-state image pickup element chip 1 can besuppressed.

[0031] (Second Embodiment)

[0032]FIG. 4 is a sectional view of a solid-state image pickup deviceaccording to the second embodiment of the present invention. In FIG. 4,portions that are identical to those of FIG. 1 are denoted by the samereference numerals as in FIG. 1. FIG. 4 shows a state wherein asolid-state image pickup element chip 1 is fixed to a substrate 4 with aflexible adhesive 11.

[0033] For example, the adhesive 11 is made of an urethane-, silicone-,styrene-, ester-, vinyl chloride-, or epoxy-based resin, and preferablyhas a modulus of elasticity of 1,000 MPa or less. In this embodiment,the solid-state image pickup element chip 1 is fixed to a predeterminedposition of the substrate 4, so positioning which is necessary whenattaching the solid-state image pickup device to a camera becomes easy.Also, since the adhesive 11 that fixes the solid-state image pickupelement chip 1 has flexibility, it does not cause a warp in thesolid-state image pickup element chip 1.

[0034] (Third Embodiment)

[0035]FIG. 5 is a sectional view of a solid-state image pickup deviceaccording to the third embodiment of the present invention. In FIG. 5,portions that are identical to those of FIG. 1 are denoted by the samereference numerals as in FIG. 1. In FIG. 5, a glass substrate 12 made ofthe same material as that of a protection cap 3 is used. The glasssubstrate 12 has light transmission properties. Hence, a light-shieldingfilm 13 is formed on the inner surface of the glass substrate 12 sounwanted light will not enter from the lower surface of the solid-stateimage pickup device.

[0036] The light-shielding film 13 is formed on the entire surface oronly the periphery of the glass substrate 12 to surround a solid-stateimage pickup element chip 1. In this embodiment, since the protectioncap 3 and glass substrate 12 are made of the same material, no warp iscaused in the solid-state image pickup element chip 1 by a difference inthermal expansion coefficient. Since the light-shielding film 13 isformed on the glass substrate 12, incident light from the lower surfaceof the solid-state image pickup device can be prevented.

[0037] The light-shielding film 13, the glass substrate 12, and thesolid-state image pickup element chip 1 may be adhered to each otherwith an adhesive 11. Alternatively, a flexible adhesive that can shieldlight may be used as the light-shielding film 13, and the glasssubstrate 12 and solid-state image pickup element chip 1 may be adheredto each other through the light-shielding adhesive. Alternatively, thelight-shielding film 13 may be formed on the solid-state image pickupdevice shown in FIG. 4.

[0038] (Fourth Embodiment)

[0039]FIG. 6 is a sectional view of a solid-state image pickup deviceaccording to the fourth embodiment of the present invention. In FIG. 6,portions that are identical to those of FIG. 1 are denoted by the samereference numerals as in FIG. 1. In FIG. 6, a contact preventive member14 is formed around a solid-state image pickup element chip 1 from aflexible resin.

[0040] For example, the contact preventive member 14 is formed bythermally bonding a thermoset resin, applied to a protection cap 3 inadvance and rendered B-stage, to the solid-state image pickup elementchip 1 and a substrate 4. The thermoset resin is rendered B-stage inorder to prevent it from spreading to a light-receiving surface 7 duringthermal bonding. In place of a thermoset resin, a thermoplastic resinmay be used.

[0041] For example, the contact preventive member 14 is made of aflexible resin such as an urethane-, silicone-, styrene-, ester-, vinylchloride-, epoxy-, or phenol-based resin, and preferably has a modulusof elasticity of 1,000 MPa or less. In this embodiment, the contactpreventive member 14 is adhered to the periphery of the solid-stateimage pickup element chip 1. Alternatively, the contact preventivemember 14 may be formed outside the solid-state image pickup elementchip 1, and be adhered to only the protection cap 3 and substrate 4.

[0042] In this embodiment, since the contact preventive member 14 isformed to surround solid-state image pickup elements 7, a sealing resin8 does not enter the solid-state image pickup elements 7. Hence, theselection of the material of the sealing resin 8 is widened. Since thecontact preventive member 14 is made of a flexible resin, no warp occursin the solid-state image pickup element chip 1.

[0043] As has been described above, according to the present invention,a solid-state image pickup element chip is formed on a substrate with athermal expansion coefficient equal to that of a protection cap, and thesubstrate and protection cap are sealed with a sealing resin.Alternatively, a solid-state image pickup element chip is formed on asubstrate made of the same material as that of a protection cap througha light-shielding layer that shields light, and the substrate andprotection cap are sealed with a sealing resin. Therefore, no warpoccurs in the solid-state image pickup element chip.

What is claimed is:
 1. A solid-state image pickup device comprising: asolid-state image pickup element chip on which a plurality ofsolid-state image pickup elements are mounted; and a protection capprovided on a light incident side of said solid-state image pickupelement chip and adapted to protect said solid-state image pickupelement chip, characterized in that said solid-state image pickupelement chip is formed on a substrate with a thermal expansioncoefficient equal to that of said protection cap, and the substrate andsaid protection cap are sealed with a sealing resin.
 2. The deviceaccording to claim 1, characterized in that said solid-state imagepickup element chip is adhered onto the substrate with a flexibleadhesive.
 3. The device according to claim 1, characterized in that acontact preventive member is provided between each one of the pluralityof solid-state image pickup elements and the sealing resin so thesealing resin will not come into contact with each one of the pluralityof solid-state image pickup elements.
 4. The device according to claim1, characterized in that the substrate is one of a glass substrate,ceramic substrate, metal substrate, and resin substrate, or a substrateformed by stacking some of the glass substrate, ceramic substrate, metalsubstrate, and resin substrate.
 5. The device according to claim 1,characterized in that the sealing resin is a resin selected from thegroup consisting of epoxy-, acrylic, and phenol-based resins.
 6. Thedevice according to claim 1, characterized in that said solid-stateimage pickup element chip is formed on the substrate through alight-shielding layer that shields light.
 7. A solid-state image pickupdevice comprising: a solid-state image pickup element chip on which aplurality of solid-state image pickup elements are mounted; and aprotection cap provided on a light incident side of said solid-stateimage pickup element chip and adapted to protect said solid-state imagepickup element chip, characterized in that said solid-state image pickupelement chip is formed on a substrate made of the same material as thatof said protection cap, and the substrate and said protection cap aresealed with a sealing resin.
 8. The device according to claim 7,characterized in that said solid-state image pickup element chip isadhered onto the substrate with a flexible adhesive.
 9. The deviceaccording to claim 7, characterized in that a contact preventive memberis provided between each one of the plurality of solid-state imagepickup elements and the sealing resin so the sealing resin will not comeinto contact with each one of the plurality of solid-state image pickupelements.
 10. The device according to claim 7, characterized in that thesubstrate is one of a glass substrate, ceramic substrate, metalsubstrate, and resin substrate, or a substrate formed by stacking someof the glass substrate, ceramic substrate, metal substrate, and resinsubstrate.
 11. The device according to claim 7, characterized in thatthe sealing resin is a resin selected from the group consisting ofepoxy-, acrylic, and phenol-based resins.
 12. The device according toclaim 7, characterized in that said solid-state image pickup elementchip is formed on the substrate through a light-shielding layer thatshields light.